The overall objectives of this research are to determine if alterations of immune regulation in chronic active hepatitis are genetic, represent immunological antecedents of chronic active hepatitis and provide markers for genetic susceptibility and defintion of subsets of patients based on an immunopathogenetic classification. In order to accomplish these objectives, measurements of immunoregulatory function in conjunction with HLA A, B and DR phenotypes and immunoglobulin (Gm, Am, Km) allotypes will be performed in patients with chronic hepatitis and their first degree relatives. To test the hypothesis that decreased suppressor cell activity is an inherited abnormality in certain forms of chronic active hepatitis genetic analyses of segregation of suppressor cell activity will be performed. Linkage analysis will be applied to quantitate the degree of association between HLA loci, immunoglobulin allotype loci and loci marking suppressor cell activity.